Manufacture of steel sheets



Patented Apr. 19, 1927.

UNITED STATES PATENT OFFICE.

.WILLIAM E. C AUGHERTY F NATRONA,

PENNSYIJFANIA, 'A-SSIGNOR, IBY mnsnn AS- SIGNMENTS, TO- ALLEGHENY STEELCOMIANY, OI BRACKENRIDGE, PENNSYL- VANIA, A CORPORATION OF PENNSYLVANIA.

MANUFACTURE OF STEEL SHEETS.

N'o Drawing.

This inventionrelates to'the manufacture of steel sheets andparticularly to the manufactureofsteel sheets suitable for use wheredifiicult stamping or drawing operations are necessary.

In the ordinary manufacture of such sheets, the ingot is rolled in astandard three high mill into a sheet bar which is eutinto suitablelengths for completion into sheets.

The length of the cut bars becomes the width of the sheets and becauseofthis, the rolling of the sheets takes place atright angles to thedirection of rolling of the bars. This cross rolling, to some extent,causes a refinement of thegrain structure of the sheets. Thisrefinement, however, is only relative,

because the rolling at the sheet mill is done at low temperatures andtherefore the elongation of thegrain is still pronounced.

employed in 'rollin this class of sheets and the methodutilize dependson the quality of surface desired. .One method is the socalled, tightrolling method and the other, the loose rolling method.

In the tight rolling method,-the bars are roughed down on the roughingmill, matched or paired, depending on the gauge and size, reheated andfinished to length 'on a finishing mill. In this method, the sheets arealways'stuck together so that the rolling operation is yirtua] y thesame as though the combined sheets existed as one plate. The

scale elongates'fairly uniformly with the elongation of the sheets and;a fairly satisfactory surface can ordinarily be obtained. It frequentlyhappens, however, that -isolated areas of surface scale become detachedand cause defective spots on the sheet and in opening the sheets aftershearing, it frequently happens that this scale. does not spread evenlyover the surface ofadjacent s eets, and causes a grainy 'or. wood-likesurface.

he loose rolling method was evolved in order to overcome the defects inthe tight rolling method. Inth'e loose rolling method, the sheets areroughed down to approxi- "matel one-half their final length. They are ten pickled to remove the scale and dipped in an emulsion of charcoal andwater.

A coated sheet is then sandwiched between two uncoated sheets and thepack is heated to a relatively low teinperature and finished Applicationfiled. June 18,

There are two distinct methods at present have the advantages' pf boththe present 'tomary in the tight rolling method,.thc

structure of the steel is very much distorted with the result that it isvery diflicult to refine the steel by subsequent annealing. The smoothglassy surface of the loosely rolled sheets adds to the difiiculty offinal annealing, since after the sheets are pickled, they have a greattendency to stick together when annealed in bulk as in'commercial boxannealing. In order to avoid this sticking, it is customary to annealimmediately after rolling; the original scale on the sheet serves toprevent the sheets 1 from sticking. This annealing is done at a hightemperature in order to get as much refinement as possible. Since it isnecessary to picklev the scale ofl? after annealing it becomes necessaryto give the sheets a second anneal to remove the hydrogen which has beenabsorbed from the picklin operation.

An 0 ject of this invention is to provide a method of rolling s'teelsheets which will tight and loose rolling methods without thedisadvantages of either.

'A further object is to provide a'relatively cheap method of rollinghigh grade steel sheets suitable for difficult stamping and drawingoperations. These, as well as other objects which will readily appear tothose skilled in this particular art," I attain by means of the methoddescribed in the spec'- ification forming part of this a plication.

In carrying out my improve method, the sheets are roughed down toapproximately one-half their finished lengt They are then singlyannealed in a standard blueanneal urnac operated continuously at atemperature sufliclently high to completely transform the rain ornormalize the structure. After this anneal, the sheets are pickled andthen coated by being dipped in an emulsion of charcoal and water. Theyare then matched or paired and raised to a relatively low rollingtemperature and rolled to length.

The final rolling while at a relatively low temperature does not distortthe structure which has been produced by the annealing operation, sincethe sheets are approxin'iately one-half the finished length at thecommencemcnt of the final rolling operation, the work necessary beingrelatively slight.

If cold rolling is desired, this can be interjected either beforepickling or after pickling.

I have found that the structure produced by this method is much superiorto that obtained by either the present tight or loose rolling method.

By this method it is possible to considerably chcapon the production ofhigh grade sheets. Instead of rolling the ingot into a bar and roughingthe bar down in the sheet mill with high priced labor as is nowcustomary, I roll the ingot into slabs in a slab mill and convert theseslabs into blue-annealed plates or sheets of large size which can beannealed and subsequently sheared to sizes suitable for the sheet millfinishing operations. These sheared plates or sheets, after beingpickled, become the raw stock for the sheet mill operation, and, sincethe final rolling is of relatively short duration, it is obvious thatthe roduction of the sheet mill is considerab y increased. The crews arereduced for the reason that it is not necessary to heat and rough downthe bars, and since this labor is considerably higher than that employedin rolling the blue-annealed plates or sheets, I accomplish aconsiderable reduction in cost.

From the above, it will be seen that I carry on the final rollingoperation only, in the sheet mill. In all other steps I employ thestandard commercial operations used in the production of blue-annealedsheets.

By way of example: If it is desired to produce a 20 gauge sheet 36"XlOOlong.

produce in the blue annealed plate and sheet department a blue annealedand pickled sheet 36"1-160 long of a gauge suflicient to produce a 20gauge sheet when rolled to 120". These sheets I furnish to the sheetmill department where they are dipped in an emulsion of charcoal andwater, matched or paired, heated to a relatively low temperature androlled to length in one operation.

In this method, the ingot is bloomed down into slabs by rolling in onedirection. The slabs are sheared so that the length of the shearedpieces" becomes the Width of the blue annealed plate or sheet; thesecond operation being at right angles to the first operation. After theslab has been converted into a blue annealed plate or sheet, it issheared to size for the sheet mill opera tion in such manner that thefinal rolling is at right angles to the second rolling operation. or inthe same direction as the first.

inaasei I find that this has a tendency to benefieially influence thesize of the grain and materially toughen the final product.

Having thus described my invention, What I claim is:

1 The method, which consists in roughing down steel sheets toapproximately onehalf their finished length, in annealing the rougheddown sheets at a temperature sufficiently high to transform the grainstructure thereof, in pickling said annealed sheets, in matching orpairing the roughed down sheets, in rolling the paired or matched sheetsto length, in pickling the sheets after rolling and then in annealingthe same.

2. The method, which consists in roughing down steel sheets toapproximately one-half their finished length, in annealing the rougheddown sheets at a temperature sulficiently high to normalize the grainstructure thereof, in pickling said annealed sheets, in matching orpairing the roughed down sheets, in loose rolling the paired or matchedsheets to length, in pickling the sheets after loose rolling and then inbox annealing the same.

3. The method, which consists in roughing down steel sheets toapproximately one-half their finished length, in singly annealing theroughed down-sheets at a temperature sufiiciently high to normalize thegrain structure thereof, in pickling said annealed sheets, in matchingor pairing the roughed down sheets after preparing the same to preventsticking during rolling, in rolling the paired or matched and treatedsheets to length, in pickling the sheets after rolling and then in boxannealing the same.

4. The method, which consists in roughing down steel sheets toapproximately onehalf their finished length, in annealing the rougheddown sheets at a temperature sufficiently high to normalize the grainstructure thereof, in pickling said annealed sheets, in matching orpairing the roughed down sheets, in loose rolling the paired or matchedsheets to length, in pickling the loose rolled sheets, in cold rollingthe sheets either before or after said second pickling and then inannealing the same.

5. The method, which consists in roughing down steel sheets toapproximately onehalf their finished length, in singly annealing theroughed down sheets at a temperature sufliciently high to transform thegrain structure thereof, in pickling said annealed sheets, in looserolling the paired or matched sheets to length, in pickling the looserolled sheets, in cold rolling the sheets either before or after saidsecond pickling and then in box annealing the sheets.

In testimony whereof, I have hereunto subscribed my name this 12th dayofJune,

WILLIAM E. GAUGHERTY.

